1. Field of the Invention
A method utilized in a wireless communication and related communication device are disclosed, and more particularly, to a method of handling long term evolution positioning protocol data in a wireless communication system and related communication device.
2. Description of the Prior Art
A long-term evolution (LTE) system, initiated by the third generation partnership project (3GPP), is now being regarded as a new radio interface and radio network architecture that provides a high data rate, low latency, packet optimization, and improved system capacity and coverage. In the LTE system, an evolved universal terrestrial radio access network (E-UTRAN) includes a plurality of evolved Node-Bs (eNBs) and communicates with a plurality of mobile stations, also referred as user equipments (UEs).
In the LTE system, a LTE Positioning Protocol (LPP) is set up between the UE and an evolved serving mobile location centre (E-SMLC) for determining the result of the positioning for the UE. The LPP is a point to point positioning protocol and supports positioning and location related services (e.g. transfer of assistance data) for the UE accessing E-UTRAN. To avoid creating new positioning protocols for future access types developed by 3GPP, and to enable positioning measurements for terrestrial access types other than E-UTRAN, LPP is in principle forward-compatible with other access types, even though restricted to E-UTRAN access.
According to the LTE specification for the LPP layer, several scenarios may occur and are described as follows.
In the first scenario, a non-access stratum (NAS) layer and the LPP layer are over a radio resource control (RRC) layer. Therefore, when a radio resource control (RRC) layer of the UE or the eNB has a LPP message and a NAS message to transmit, the LTE system does not clearly specify that RRC shall transmit the LPP message or the NAS message first. In other words, how to prioritize transmission of the LPP message and the NAS message is never concerned. If the NAS message (e.g. SERVICE REQUEST) transmission is delayed due to transmission of the LPP message, the call establishment (e.g. a mobile terminating call, a mobile originating call, or an emergency call) is delayed.
In the second scenario, the UE may transfer a LPP protocol data unit (PDU), to the E-SMLC via the eNB, whereas the E-SMLC may transfer the LPP PDU to the UE via the eNB. The UE or the eNB may not transmit LPP PDU successfully (e.g. interrupted by a handover or a RRC connection re-establishment due to a radio link failure). The LTE system does not clearly define how to deal with this situation, thereby causing LPP PDU loss.
In the third scenario, the network may release a NAS signaling connection with the UE. To allow the network to release the NAS signaling connection, the UE starts the timer T3440. When the timer T3440 expires, the UE releases NAS signaling connection and a RRC connection. If the UE transmit the LPP PDU during a running period of the timer T3440, the LPP PDU transmission may be failed due to T3440 expiry (i.e. RRC connection release).